Drop the "No Glyph" glyph

[alerque]

I've been doing tests with mono-space fonts in my terminal that include double width characters. These are actually pretty common as poor-man's-ligatures in programming contexts. One thing I've run across that's really obnoxious is a handful of fonts that have placeholder glyphs rather than no glyphs for unimplemented code points. I'm sure this is a well intentioned attempt to un-confuse people running across the dreaded empty boxes — and in some contexts it is a cute fix, but in others it is obscenely obnoxious — such as when what you are trying to do is make use of font fallbacks such as almost all modern operating systems and typesetting systems support (even vim in my terminal!).

Another thing that is going to wreak havoc with is automated tooling to determine and render specimens for font coverage. You can't easily figure out what is implemented if there are fillers.

I propose entirely nuking the "No Glyph" glyph and leaving unimplemented glyphs as non-existent so that other tools can figure out what to do with them.

In my opinion these are to fonts what null is to programming languages: a billion dollar mistake. Not as costly but still an ultimate downgrade in function just because you couldn't resist.